Jack stands have been utilized for many years to support various types of raised loads. For example, often it is necessary for the home handyman to utilize a usual jack or other suitable lifting equipment such as ramps, for raising an automobile to be repaired to gain access to the parts in need of repair. However, such lifting equipment often is unsuitable for safely supporting the load in the raised position. Thus, one or more jack stands are positioned usually under the frame or axles of the raised vehicle, and the extensible post of each stand is raised to the appropriate height and locked at such height to support the vehicle in the raised position. It can be seen that in such applications the adjustability and positive locking of the stand at the desired height are very important features. Moreover, the strength and stability of the jack stand also are very critical features for obvious safety reasons.
In recent years, jack stands have become popular items in auto part stores, discount stores and the like, and are purchased for supporting automobiles, boat trailers, camping trailers, etc. Since cost is a primary consideration to most consumers, the jack stand must be low-cost and effective in use, as well as durable and safe.
The known prior art includes numerous jack stands which utilize various types of locking means to adjustably support the jack stand post at a selected height. U.S. Pat. Nos. 1,499,280; 2,439,854; 3,355,136; 4,009,855; and 4.042,202 all disclose jack stands having separate locking pins adapted to be manually slideably engaged with longitudinally spaced openings formed in the jack stand post and with the base of the stand in some manner for supporting the post at a desired height. U.S. Pat. No. 1,416,896 discloses the same general concept as the above-listed patents, except that the locking pins thereof are part of the jack stand assembly and are spring-biased. U.S. Pat. Nos. 3,493,209 and 4,141,526 disclose jack stands having threaded adjustable posts. U.S. Pat. Nos. 2,514,095 and 4,021,012 disclose jack stands having a pivoting hook and a tooth and recess locking mechanism, respectively. U.S. Pat. No. 3,970,278 merely discloses a particular base construction for a jack stand.
The closest known prior art to my ratchet jack stand of the present invention is disclosed in U.S. Pat. Nos. 3,599,923 and 3,802,658. However, there are important differences between the respective ratchet jack stands disclosed in these patents and my improved ratchet jack stand. The jack stand of U.S. Pat. No. 3,599.923 has a pawl or hook-like member which is adapted for positive locking engagement with an adjustable post. The pawl is releasable from the post by a lever when downward adjustment of the post is desired. In contrast, the present invention utilized a pin attached to a gravity-biased handle for positive locking engagement with an adjustable post. Although the handle is used to release the pin from engagement with the post when downward adjustment of the post is required, the gravity biased handle also is important since the weight of the handle biases the pin toward the locked or post-engaged position at all times.
Although the jack stand of U.S. Pat. No. 3,802,658 uses a pin to lockingly engage a notched post, the pin is not biased in the direction of positive locking engagement by a pivotally mounted gravity-biased handle as is the locking pin of my invention, but rather is spring-biased.
Therefore, the need exists for an improved ratchet jack stand having a gravity-biased positive locking ratchet mechanism for adjustably supporting the jack stand post at a predetermined height to support a raised load.